In recent years, touch panels have been incorporated in many information terminal devices such as mobile phones. An information terminal device incorporating a touch panel detects touch by a user on a screen displaying information so as to receive an operation input. This enables the user to operate the device instinctively, which improves convenience of the information terminal device.
The touch panels detect touch with various systems. Recently, electrostatic capacitive touch panels (hereinafter, referred to as “electrostatic touch panels”) that detect a change in an electrostatic capacitance by touch have become mainstream and have been incorporated in many information terminal devices. An electrostatic touch panel can detect what is called multi touch, that is, touch on a plurality of positions at the same time. Note that because the electrostatic touch panel detects a change in the electrostatic capacitance, the electrostatic touch panel can detect touch with a conductor such as a user's finger but has difficulty in detecting touch with an insulator.
For example, some types of automated teller machines (ATMs) of banks employ a resistance film touch panel (hereinafter, referred to as “resistive touch panel”) using two film electrodes opposed to each other with a space interposed therebetween. If two film electrodes (hereinafter, referred to as “resistance films”) make contact with each other with a pressure generated by touch and an electric current flows in between the resistance films, the resistive touch panel obtains a resistance from the current so as to specify touched coordinates. That is to say, the resistive touch panel can detect touch coordinates if the resistive touch panel is touched with pressure equal to or higher than a certain pressure level regardless of whether the touching subject is a conductor or an insulator. Note that because the resistive touch panel detects the touch coordinates from the resistance, the resistive touch panel has difficulty in detecting a plurality of sets of touch coordinates when the multi touch has been made.
The respective touch detection systems have advantages and disadvantages as described above, and a combined use of touch panels employing a plurality of systems has been also considered. For example, the above-mentioned electrostatic touch panel and resistive touch panel can be superimposed on each other so as to detect touch with a conductor by the electrostatic touch panel and detect touch with an insulator by the resistive touch panel. An example of related art is described in Japanese Laid-open Patent Publication No. 07-334308.
In many information terminal devices, it is desired that more complicated and advanced operations can be performed by the touch panel with impressive progress of software and hardware in recent years. To be more specific, in tablet information terminal devices, for example, if keys equivalent to the keyboard of a personal computer and the like are made to be displayed on the touch panel so as to enable a user to perform operations of what is called touch typing and the like, operability of character input and the like is improved. In order to make it possible to perform the operations, the information terminal device performs processing of determining a key that has been pressed strongly with any one of a plurality of the user's fingers placed on the touch panel.
Furthermore, multiple touch detection processing is usable in some cases. As the multiple touch detection processing, the touch with a user's finger is detected at the time of key input and the touch with a pen is detected at the time of handwriting input of characters and the like, for example. Furthermore, when the touch with the pen is detected, it is preferable that the touch with the pen and the touch with a user's hand holding the pen are distinguished in consideration of the state where the user's hand holding the pen is placed on the touch panel. In this manner, when the touch panel is used, the touch panel may be touched in various modes depending on the situations. For this reason, in order to enable a user to perform complicated and advanced operations by the touch panel, the touch modes are required to be determined accurately.
There is no example where the technique of determining the possible touch modes when touch panels of a plurality of systems are used in combination is examined comprehensively. It is difficult to determine various touch modes depending on the situations accurately. For this reason, even if touch panels of a plurality of systems are combined, intention of the user for the touch is not reflected to the processing accurately. This arises a problem that there is certain limitation on improvement of convenience of the information terminal device.